| Popis: |
In shift gearboxes, audible vibrations can arise during the process of clutch engagement. Measurements show an unstable axial motion of the gear unit input shaft. In order to explain this effect, an approach which establishes the interaction of the slipping clutch and the gearing is proposed. The suggested model consists of a pressure plate, a clutch disc, a gear unit input shaft and a tooth contact. The gear unit input shaft is rigidly connected to the gearing and the clutch disc and has translational and rotational degrees of freedom. The tooth contact imposes a kinematic constraint on the system. This is why the sliding friction torque is transformed into forces in axial and radial direction of the shaft. Depending on the gearing parameters and the slip, the contact normal force between clutch disc and pressure plate is amplified (motor accelerating) or reduced (motor slowing down) by the toothing. For both shifting situations, a region of flutter instability in the parameter space can be found. The dynamic behavior of the system with parameters in the latter region is analyzed. It is shown that there exists a stable piecewise-continuous limit cycle: During one period, the contact between the clutch disc and the pressure plate opens shortly. A variation of parameters is performed to show the dependence of the limit cycle on the geometry and on the operation conditions. |
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